It is common, after 20 plus years and COUNTLESS shifting, for this spring to finally stress fracture in half, or at the very least lose the tension it was designed to have, making it not function as it should. At the very least making shifting not as precise and fun as it should be, and at the most causing internal transaxle damage due to not returning the Shift Shaft assembly back to its neutral state.

This is the spring found on the round steel rod on the end of the Shift Shaft Assembly. The Shift Shaft Assembly is the unit the shifter cables attach to at the transaxle.
Inside the transaxle the end of the Shift Shaft has a round steel rod that inserts into a round hole.
This Shift Shaft Return, to neutral, Spring installs on this rod before inserting it into the transaxle.
This spring is what is responsible for returning the Shift Shaft Assembly back to a neutral state. Changing gears, and while the transaxle is holding the selected gear in place, this spring is what also gives you the spring feeling as you push the shifter inside the car over to pairs of gears. When you push the shifter over to select either 1st or 2nd the Shift Shaft Assembly is being pushed towards, into, the transaxle compressing this spring where it remains compressed as the shit shaft will remain in this position through 1st and 2nd.
Then when shifting out of 2nd and into neutral, this is the spring responsible to push the shift shaft up towards the outside of the transaxle. With an old tired return spring, or one that has finally snapped into pieces, the Shift Shaft Assembly will not be capable of being pushing back up/out into the neutral position.

Replacing this tired, missing, or broken spring with this new Genuine Mitsubishi Getrag return Spring means it has the exact length and spring/tension to it so that it will return the Shift Shaft Assembly exactly where it was engineered to return to.

It's a small and often overlooked part that gets constant wear and tear and helps return your Getrag transaxle to like new operation. What seems like a small insignificant part plays a crucial role in the transaxle operation and shifter feel.

Using an off he shelf hardware store spring can cause damage to your transaxle internals and at the very least won't give you the like new feeling/operation because it won't have the correct spring rate. Plus this Genuine part is cheap, no reason to rig your expensive transaxle when a part is available at an affordable price.